Luiz featured for City during their pre-season fixtures
Manchester City boss Pep Guardiola is "sad and disappointed" that Douglas Luiz will not be allowed to play this season after the 20-year-old Brazilian's work permit was rejected.
City reportedly sent the Football Association video footage supporting Luiz's application but to no avail.
The FA made their decision on Thursday, the day the transfer window shut.
"I accept the rules but it's difficult to understand. They don't know him," Guardiola said.
"They have to judge if he has the ability to decide. Me and can't say Pep won't go because of the salary because for that he has to look at me and know everything.
"So no, I'm a little bit disappointed because he cannot say that I cannot count on [sic] because his salary is amazing, to know that he has to know my salary."Analysis
BBC Sport's Simon Stone
Luiz did not automatically qualify for a work permit, so Manchester City had to apply for an exemption.
However, because Luiz only started one league game on loan with Girona, the FA, who have responsibility for granting exemptions, decided the Brazilian wasn't worth it.
Guardiola has said Luiz will now be loaned out again although, wherever he goes, unless the youngster actually plays on a regular basis, he is not going to get his work permit next year either.